Scientists build optical switch to induce ‘dream sleep’

A group of American scientists can literally put the brain into a certain sleep mode. In mice they built an optical switch that can be switched with a laser, in order to put the animals into REM sleep. This state is usually where most dreams occur.

The research was conducted by the University of California at Berkeley and published in the authoritative scientific journal Nature. In summary, the scientists have found a way to induce REM sleep in laboratory animals. They do this by activating certain neurons in a brain region called the medulla. This particular group of neurons does their job by producing the neurotransmitter GABA and has been suspected of playing an important role in inducing REM sleep.

To investigate the precise role of these neurons, the Berkeley researchers built an optical switch in the brains of mice. When this switch was turned on, by means of laser light, the neurons in the medulla were activated, after which the scientists discovered that REM sleep set in after just a few seconds.

The switch is built by using viruses that are able to infect a specific type of neurons, and then insert genes into the DNA that produce special channels. After production in the cell nucleus, these channels move to the cell surface and can open themselves when they are stimulated by a light signal, in this case from a laser. After opening, ions flow into the cell and neuronal activity is increased.

Rem is an abbreviation for rapid eye movement, and is a ‘sleep mode’ characterized by relatively high brain activity. Most dreams are induced in this state and are also the most intense. By activating REM sleep, it is therefore also possible to stimulate dreams. Incidentally, the mice in the study had to have fallen asleep first for the switch to do its job: turning on the switch in awake mice only made them eat more.

According to the researchers, the optical switch can be used to research REM sleep. Much is still unknown about the exact functioning and function of sleep. Theoretically, the technique could also be used to induce dreams, but such plans do not appear to have been formulated. Applications in humans also do not appear to be on the agenda for the time being.